This invention relates to removing lining from a well and more particularly to methods, systems and components for use in removing plastic lining from metal tubing in a well. One specific application is with polyurethane lining in metal casing cemented in a well.
In constructing a well from which liquid or gas is to be produced, various types of tubing strings can be put in the drilled borehole. One type is typically called xe2x80x9ccasing.xe2x80x9d Traditionally this has been a metal tubing having a relatively large inner diameter that allows other tubing strings to be lowered through it. One way to use casing is to lower it into the borehole and then pump cement such that the cement is placed in the annulus between the casing and the wall of the borehole. These operations are performed using well-known techniques.
Another type of tubing string that has been used is a smaller diameter string that is run into the well inside previously installed casing. Such a narrower string might be used to produce oil or gas from the well to the surface, for example. Another example is that such a string might be used to inject substances into the well, such as in a technique referred to as xe2x80x9csecondary recoveryxe2x80x9d in which the injected substance pushes hydrocarbons out of the well (or out another well or other wells).
More recently, a different type of casing has been used in some applications. This type of casing includes the traditional metal tubing, but one lined with plastic. The plastic lining is typically made of a thermoplastic polymer, a non-limiting example of which is polyurethane. With this type of casing, some substances can be produced from or injected into a well without the use of the traditional inner production or injection tubing string referred to in the immediately preceding paragraph. The inner diameter of the lined casing is larger than the inner diameter of the traditional production or injection tubing; therefore, more production or injection per unit of time can be obtained through the lined casing alone than through the narrower traditional production or injection string. That is, higher volumetric flow rates can be obtained through the lined casing. This type of casing has been used, for example, in producing gaseous carbon dioxide from a first well and in injecting it into a second well in a secondary recovery process for driving liquid or gaseous hydrocarbons out of the second well or out of the formation intersected by the second well.
The lined casing application referred to above, in which no separate inner tubing string is used, has advantages over the traditional casing plus production/injection string technique. In addition to the larger flow advantage mentioned above, the lined casing can be used less expensively. Furthermore, the lining is more resistant to corrosion than the metal casing. Such lining can be used to cover damaged casing walls.
Although there are at least the aforementioned advantages, the plastic lining can be damaged during installation and sometimes the metal casing may corrode or deteriorate sufficiently that it needs to be repaired even though it may be covered by the lining. When this damage or deterioration occurs, the lining needs to be pulled out of the outer metal tubing and a new lining installed (and possibly repairs made to damaged metal tubing). Although the outer metal tubing is typically cemented into the well borehole, the lining is retained in the metal tubing by its own outwardly directed force and friction. That is, the lining is not glued or otherwise separately adhered to the metal tubing. Rather, the lining is inserted in known manner into the metal tubing in a radially inwardly compressed state; once installed, the resilient lining (having an uncompressed outer diameter larger than the inner diameter of the metal tubing) expands against the inner surface of the metal tubing so that the lining is held by the radially outward force exerted by the lining and friction between the outer surface of the lining and the inner surface of the tubing. At the mouth of the well, a plastic flange is fused to the upper end of the lining to also provide support. In view of the foregoing reasons why lining sometimes needs to be removed, and since the outer metal tubing is cemented in the borehole, there are the need for a system and method for removing lining from the tubing and the need for components for such system and method.
Although my prior inventions disclosed in U.S. patent application Ser. No. 09/256,021 and U.S. patent application Ser. No. 09/584,954 are directed to satisfying the aforementioned needs, I have developed improvements and enhancements meeting additional needs. Such needs include providing for reaming lining material prior to removal, enabling cooling or lubricating fluid to be conducted during reaming, permitting interchangeability of different outer annular cutters with a reamer, improving the longitudinal cutting of the lining, providing alternative types of separate or integrated spearing devices or inner engagement members adapted to different uses (e.g., navigating through bent lining), and enabling synchronous movement among components.
The present invention satisfies the aforementioned needs by providing a novel and improved lining removal method, system and components thereof.
The present invention provides for reaming lining material prior to removing it from a tubing in a well. The present invention enables cooling or lubricating fluid to be conducted during reaming. It also permits interchangeability of different outer annular cutters with a reamer.
The present invention provides improved longitudinal cutting of the lining. It particularly provides for the lining to be cut along a spiral path to facilitate removal. Part of the cutting implement passes between the lining and the tubing to assist in removing or loosening the lining from the tubing.
Different functions may need to be performed during removal; therefore, the present invention provides alternative types of separate or integrated spearing devices or inner engagement members adapted to such different uses. For example, one form of novel and improved spearing device facilitates navigating through bent lining within the tubing. As another example, inner engagement elements can be integrated with an outer overshot sleeve to provide an integral engagement and removal structure.
Another form of the invention connects all the components to enable synchronous movement such that all move at least rotationally together.
The present invention provides an overall method of removing lining from a tubing in a well. This method comprises: reaming at least a portion of material within a lining in a tubing in a well; cutting at least a segment of the lining along a spiral path; engaging the lining for applying a pulling force to the lining; and applying a pulling force to lift the engaged lining out of the tubing. Individual aspects of this also form parts of the present invention. Following are examples.
A lining reamer comprises a reamer body having a forward end and a longitudinal passage defined through the reamer body to an opening at the forward end. The forward end includes milling structure to mill plastic material of lining in a tubing in a well such that the milled plastic material forms a strand that passes into the opening and up the passage in the reamer body. Another definition includes an apparatus to excavate lining in a tubing in a well, which apparatus comprises: a reamer body having a forward end; and a cutter ring releasably connected to the reamer body. Preferably the cutter ring is a selected one of a plurality of cutter rings each having the same inner diameter such that each is releasably connectable to the reamer body, but each having a different outer diameter. A related method of excavating material of a lining in tubing in a well comprises: rotating circularly disposed inner cutting elements against a radially inwardly disposed annular portion of the material; rotating circularly disposed outer cutting elements against a radially outwardly disposed annular portion of the material; and rotating reaming elements extending between the inner cutting elements and the outer cutting elements.
A cutting tool to cut lining in tubing in a well comprises a cutter blade including a cutting edge to cut into lining in tubing in a well and further including an angled surface disposed with the cutting edge such that interactive engagement between the lining and the angled surface during cutting by the cutting edge rotates the cutter blade relative to the lining. This is preferably transported into and out of the well on a blade carrier, such as one including a mandrel, a first sleeve disposed on the mandrel, and a second sleeve disposed on the mandrel and connected to the first sleeve such that the first and second sleeves can rotate relative to each other. In this implementation the cutter blade is connected to the second sleeve. A method of cutting lining in a tubing in a well comprises: lowering a cutter blade into a well having a lining in a tubing; engaging the lining with the cutter blade; and moving the engaged cutter blade up the well such that a spiral cut is formed in the lining.
An inner engagement member for a tool for removing plastic lining from tubing in a well comprises a tapered body to navigate through a bent segment in a plastic lining in tubing in a well. The body can include a partially or fully continuously grooved outer surface. It can include longitudinally defined edges such as for reaming. It can terminate at a tip including a chisel element. It can terminate in a removable tip element.
A lining removal tool of the present invention comprises: an inner engagement member (such as one of the above); an outer engagement member; and a coupling connecting the inner and outer engagement members in fixed rotational relation to each other.
Another lining removal tool comprises: an outer engagement member; and an inner engagement member connected to an inner surface of the outer engagement member. The inner engagement member of one such embodiment includes a cutting member attached to the inner surface of the outer engagement member. The inner engagement member of another such embodiment includes a plurality of stiff wires attached to the inner surface of the outer engagement member. Related lining removal methods are also disclosed.
Therefore, from the foregoing, it is a general object of the present invention to provide a novel and improved lining removal method, system and components thereof. Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art when the following description of the preferred embodiments is read in conjunction with the accompanying drawings.